1. 1. Review- What is a compound Apply Concepts- Water (H 2 O) and hydrogen peroxide (H 2 O 2 ) both consists of hydrogen and oxygen atoms. Explain why they have different chemical and physical properties 2. Big Idea- Why do you think it is important that biologist have a good understanding of chemistry?

2. CH 2 THE CHEMISTRY OF LIFE 2.1 The Nature of Matter

3. Biology Class  You take Chemistry next year so why learn about it now  Chemistry is essential to all living things.

4.  What are you made of  When you breathe, eat, or drink, your body uses the substances in air, food, and water to carry out chemical reactions that keep you alive  Water freezing to you moving your muscles to processing thoughts.

5. Atoms  Basic unit of matter  May be broken into smaller particles that do NOT have the properties of the element.

6. Atoms  Very small- 100 million atoms would make a row only about 1 centimeter long  Consists of protons, neutrons, and electrons.

7. Atoms  Nucleus  Core of atom  Protons  Positive charge, in nucleus, mass of 1 atomic unit  Neutrons  No charge, in nucleus, mass of 1 atomic unit  Electrons  Negative charge, orbits nucleus, mass of 0 atomic units (technically a mass of 1/1840).

8. Carbon Atom  Atoms have equal numbers of electrons and protons, their positive and negative charges balance out, and atoms themselves are electrically neutral.

9.  Matter is made up of atoms  Atoms join together to make compounds  Compounds use chemical bonds to hold them together  Chemical bonds are stored energy  Molecule  Atoms of the same element joined together.

10. Elements and Isotopes  Elements and isotopes have same number of electrons  All isotopes of an element have the same chemical properties.

11. Elements  Pure substance that consists entirely of one type of atom or  Elements cannot be broken down into other types of substances  Mercury (Hg).

12. Isotopes  Atoms of the same element that differ in the number of neutrons.

13.  Atomic number  Number of protons  Atomic Number (atomic mass or weight)  Number of protons and neutrons.

14. Carbon Atom  Atomic Number 66  Mass Number  12

15. Radioactive Isotopes  Nuclei are unstable and break down at a constant rate over time  Used for  Determine the ages of rocks and fossils by analyzing the isotopes found in them  Detect and treat cancer  Kill bacteria that cause food to spoil  Labels or “tracers” to follow the movements of substances within organisms.

16. Chemical Compounds  Substance formed by the chemical combination of two or more elements in definite proportions  Water, the chemical formula H 2 O, contains two atoms of hydrogen for each atom of oxygen.

17. Chemical Compounds  Physical and chemical properties of a compound can be different from the elements that forms it  Sodium  Reacts explosively with cold water  Chlorine  Very reactive, poisonous, greenish gas that was used in battles during World War I  Sodium Chloride  Table salt.

18. Chemical Bonds  Attraction between two atoms resulting in a sharing or transferring of an electron(s)  Uses electrons  Covalent Bond  Chemical bond that SHARES electrons  Ionic Bond  Chemical bond that TRANSFERS electrons  Hydrogen Bond  Weak bond between hydrogen ions.

19. Covalent Bonds  Shares electron(s).

20. Ionic Bond  Transfer of electron(s)  Ion  A charged particle  Protons do NOT equal electrons

21. Ionic Bond  A sodium atom easily loses its one valence electron and becomes a sodium ion (Na + ).

22. Ionic Bond  A chlorine atom easily gains an electron (from sodium) and becomes a chloride ion (Cl - ).

23. Van der Waals Forces  Slight attraction can develop between the oppositely charged regions of nearby molecules  Due to unequal sharing of electrons within each molecule  Much weaker than Covalent of Ionic bonds.